Dual downhole pressure barrier with communication to verify

ABSTRACT

Apparatus and method are provided for placing a dual pressure barrier in a vertical or horizontal well and verifying by pressure sensors in the well that the pressure barriers are operable. Communication of data from the well may be by electromagnetic or acoustic signals, and the data may be acquired on a ship near the well.

This application claims priority to Provisional Application Ser. No. 61/683,749 filed on Aug. 16, 2012 and Provisional Application Ser. No. 61/701,317 filed on Sep. 14, 2012.

BACKGROUND OF INVENTION

1. Field of the Invention

This application is directed to drilling and completion of wells subsea. More particularly, apparatus and method are provided for decreasing the risk of hydrocarbons flowing from a well after it is drilled and as the well is completed for production.

2. Description of Related Art

Operations for recovering hydrocarbons from beneath the sea have expanded to many areas of the world and to ever deeper water. The drilling of wells in deep water requires large vessels with very large carrying capacity and large platforms for storage of materials and equipment. This means very high operating expenses for the drilling rigs that drill the wells. After a well is drilled subsea, the well must be “completed,” which means placing equipment in the well and at the sea floor to control flow from the well and allow further operations to be conducted in the well. Completion operations can be conducted with smaller, less expensive vessels and smaller rigs. Normally in the development of a subsea hydrocarbon reservoir, multiple wells will be drilled; it is desirable to drill and temporarily abandon each well, moving the expensive drilling rig to drill another well while using a less expensive vessel and rig to complete the first well. Ideally, completion operations may be accomplished by a small ship operating without a riser connecting the ship to the seafloor. During the time that drilling has ceased and before the well is finally ready to be produced, some of the barriers to flow in the well are removed. It is absolutely critical that fluids in zones that have been penetrated by the well be prevented from flowing up the well to the seafloor during this time.

It is commonly required by government regulations that there be at least two pressure barriers in a well at all times to prevent flow up the well. Commonly used barriers during drilling are high-density fluids and blowout preventers at the seafloor. After drilling ceases, pressure barriers are provided by mechanical plugs, packers, valves, cement plugs or other barriers known in industry.

U.S. Pat. No. 7,380,609 discloses a method for suspending, completing or working over a well by placing two pressure barriers deeper in the well than any completion tubing is to be placed in the well. The plugs are in close proximity and are said to be made independently verifiable (that both do not leak) by placement of a pressure gage between the plugs with wireless transmission of data from the gage to above the top plug and then transmission of data to surface by usual methods. U.S. Pat. No. 8,066,975 discloses a remotely actuatable valve to be placed in the bore of a tubing hanger to allow suspension of activities in a well without a dual bore riser to the surface. U.S. Pat. No. 8,082,990 discloses joining assemblies in a well with a communication line using inductive coupling to achieve signal communication across a coupling.

To install completion elements in a well without the use of a drilling rig, riser and BOP, new methods and apparatus are needed to provide at least two verifiable pressure barriers at all times. Furthermore, verification of the pressure barriers should be possible from a vessel in the vicinity of the well. Implementation of a two-barrier system will allow the offshore drilling rig to be moved after drilling operations and installation of lower elements of completion equipment (sand screens, e.g.) has been accomplished, rather than waiting for the well to be completed before moving. Deployment of upper and some lower completion elements can then be accomplished with a lower-cost special purpose vessel more efficiently adapted to completion operations, while maintaining at least two verified pressure barriers in the well at all times. The savings in cost can be millions of dollars per well.

SUMMARY OF THE INVENTION

A dual downhole barrier system having the capability of wirelessly communicating deep well pressures below and between pressure barriers in a well to the surface is provided. An intelligent well suspension plug set in the tubing hanger or casing immediately below the wellhead and capable of communicating data, including pressures and temperatures gathered at locations below the plug, to the surface is provided. A method of deploying the apparatus in a well in a single trip, along with other apparatus such as a liner or sand control screen, is also provided. A separable work string may be employed for running apparatus into a well.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic overall view of one embodiment of the apparatus in a vertical well.

FIG. 2 is a schematic overall view of one embodiment of the apparatus in a deviated or horizontal well.

FIG. 3 is a schematic overall view of another embodiment of the apparatus in a horizontal well providing a work string with an on-off attachment.

FIG. 4 is a detailed view of the “Intelligent Well Suspension Plug” with wireless communication functionality.

FIG. 5 is a view of the internal electronics to provide wireless communication functionality to the upper plug.

FIG. 6 is an isometric view of a commercial bridge plug that may be adapted to provide wireless communication to an upper plug.

FIG. 7 is an overall view of an offshore drilling rig on a semi-submersible platform connected to the seafloor with a marine riser and blowout preventer after drilling and casing of the well and drilling a productive zone below the casing is complete.

FIG. 8 is a view of the vertical well of FIG. 7 as the lower well equipment disclosed herein and a screen liner are placed in the well with a running tool.

FIG. 9 is a view of a horizontal well as the lower well equipment disclosed herein and a screen liner are being placed in the well with a running tool.

FIG. 10 shows a vertical well with communication apparatus installed and the riser and BOP still installed.

FIG. 11 is a view of a work ship near the well of FIG. 10 and an ROV deployed from the ship that may communicate with apparatus in the well.

FIG. 12 illustrates communication of data from a vertical well to a ship. (No BOP.)

FIG. 13 illustrates communication of data from a horizontal well with a lower work string in the well.

FIG. 14 shows a vertical well ready for installation of upper completion equipment.

FIG. 15 shows a horizontal well ready for installation of upper completion equipment.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, vertical (or substantially vertical) well 10, drilled below seafloor 100, is illustrated equipped with one embodiment of Dual Downhole Barrier System (DDBS) 70. “Substantially vertical” means that probe 25, suspended by cable 14, will move along the inside surface of casing 64 by gravity to be placed near enough to telemetry sub 16 to establish communication, by electromagnetic pulses or other means, between the probe and the sub. In the figures and in the description, “below” means a greater distance in the well from the top of the well. In the embodiment shown, telemetry sub 16 also includes a P/T (pressure and temperature) sensor, which is located between the downhole barriers. Alternatively, sensors that are located below lower or primary barrier valve 75 may be separately provided and in communication with sub 16. Such an embodiment would allow for three or more pressure or pressure/temperature measurements to be sent to the surface. Only two signals are discussed herein. Blowout preventer 17 is mounted on wellhead 63.

An offshore well is illustrated in most of the figures, and the apparatus and method described herein are more likely to be deployed in an offshore well, but they may also be deployed in a land well. Well 10 has been drilled, cased with surface casing 62 and production casing 64 and both casings have been cemented in place, using normal industry procedures. Intermediate casings (not shown) may also be present in the well. Well 10 has Subsea Isolation System 17 in place, which may be a smaller BOP that can be deployed from an ROV rather than the drilling BOP. Plug 30 (often referred to herein as “WiSP” or “Intelligent Well Suspension Plug”) has been placed in the well near or in a tubing hanger or other pack-off equipment 34 near ground level or sea floor 100.

Dual Downhole Barrier System (DDBS) 70 comprises polished bore receptacle 71, retrievable packer 72, secondary isolation barrier valve 73, telemetry sub 16, permanent packer (or liner hanger) 74 and primary isolation barrier valve 75. Second polished bore receptacle 77 may be used to disconnect the tubing between the packers to make operations easier if it becomes necessary to retrieve the upper portion of DDBS 70 after permanent packer 74 is set. Ported sub or sleeve or sliding sleeve 76 may optionally be placed between the packers. Sand screen 78 or other a casing liner may be run in a well below DDBS 70. Alternatively, a tubing-conveyed-type perforating gun (not shown) may be run to perforate a liner. Alternatively, pressure and temperature data may be gathered under each or either of the two barriers. These data may also be transmitted to the surface. The number of channels of data transmitted may be increased to three or more.

FIG. 2 illustrates an apparatus for highly deviated or horizontal wells. In these wells acoustic receiver probe 25, suspended by cable 14, cannot be placed by gravity near enough to telemetry sub 16 to establish electromagnetic communication. Therefore, an acoustic signal is generated by transducer 22, which preferably receives an electromagnetic signal from sub 16 and outputs an acoustic signal. Alternatively, sub 16 may output an acoustic signal instead of an electromagnetic signal. Acoustic repeaters 24 are placed outside casing 65 at operable distances to allow transmission of a signal between transducer 22 and probe 25. In general, electromagnetic communication is preferably used for short distances and acoustic telemetry is used for longer distances. A series of repeaters may be installed along the wellbore to enable effective data communication with probe 25. Acoustic receiver probe 25 preferably converts an acoustic signal to an electrical signal, which is input to upper communication plug 30 through cable 14. DDBS 70 comprises the same components as described above except for the addition of transducer 22.

WiSP 30 receives signals from probe 25 and from sensor 33. Sensor 33 is used to measure pressure in the casing between DDBS 70 and plug 30. Pressure data may then be transmitted to receiver/transmitter 19 mounted on seafloor completion equipment 17. Two channels of data may be received by communication plug 30 and transmitted to receiver/transmitter 19. Each channel may include pressure data—one from below the DDBS and one from above.

Operators of wells, and usually government regulations, require at least two independent barriers from formation pressure in place at every moment of well operations. Typically, during drilling and completions operations, this is achieved by the combination of a primary barrier, being either a deep set plug and or valve or kill weight completion fluid, combined with the drilling BOP, which provides the second barrier. The system presented herein is provided for the time after the drilling BOP has been removed. Two devices are provided for well barriers. The two barrier devices are completely ‘stand-alone’ and without interdependency in their operations. The lower barrier is the DDBS, described above. A communication plug, which is described below, may be used along with a column of kill weight completion brine as additional barriers. The system elements and components are each designed for full working pressure retention with a safety factor.

FIG. 3 illustrates a third scenario wherein a well has been drilled below the sea floor, cased and cemented and has DDBS 70 (as shown in FIG. 1) in place and is ready for completion. In the well, WiSP 30 is present. In this scenario, separable work string 201 has been placed in the well and upper work string 201(a) (not shown) has been removed, leaving lower work string 201(b), as will be explained further below and in FIG. 9.

DDBS 70 may comprise the same components as explained above and a sand screen or gravel pack (not shown) or other sand control system may be below, as explained above. The means to disconnect the tubing between packers 72 and 74 (FIG. 1) will make operations easier if it becomes necessary to retrieve the upper portion of the DDBS after permanent packer 74 is set. Or conversely, another packer/barrier valve assembly may be run in the Polished Bore Receptacle if the secondary barrier system fails to test properly.

The principal difference in this scenario is that work string 201 (FIG. 9) is placed in the well and lower work string 201(b) can serve as a communication transmission vehicle, rather than wire 14, such as shown in FIG. 2. Work string 201 includes on/off attachment 205 (FIG. 3) and the upper part of the work string has been removed from the well in FIG. 3, leaving lower work string 201(b) in the well. Lower work string 201(b) preferably has acoustic repeaters positioned on the work string as necessary to transmit acoustic pulses up the work string from the primary measurement point. These repeaters may be uncentralized repeater 212 or centralized repeater 210 or a combination of both. The function of the repeaters is to receive and reproduce the original data signal from below and send it reliably and accurately to the next repeater or receiver up-hole. A principal advantage of using the work string instead of casing is that acoustic signals are not attenuated by cement that is in contact with the casing. Lower work string 201(b) may be left in the well by use of On/Off attachment 205.

In operation, pressure and temperature data are measured in telemetry sub 16 and transmitted up the work string to WiSP 30(b), which may be adapted for use of work string 201. Where well depths make it necessary, the repeaters receive and re-transmit the data to the next station in the work string. This allows an integrated acoustic signal between DDBS 70 and WiSP 30(b). WiSP 30(b) transmits the signal to a Receiver/Transmitter 19, such as a Nautronics or Sonardyne commercial system, for relay to a vessel on the surface.

FIG. 4 shows a diagrammatic schematic of one embodiment of WiSP 30. This embodiment shows locking dogs 35 adapted to latch into casing nipple 64A. Plug 30 has fishing neck 36, which can be used for retrieval of the plug. Placing and retrieval may be by wire line, coiled tubing of pipe. When properly set, sealing system 37 engages the inside diameter of casing nipple 64A, which is preferably a polished surface. This effects a seal that is locked securely in place in the well—effectively preventing escape of any wellbore fluids. Integral to communication plug 30 is electronic gear that measures and relays pressures and temperatures from locations below the plug, ultimately to the surface. Probe 25 collects data, as described above. Any plug that is suitable for sealing the casing may be converted to a communication plug by attachment of a wireless telemetry pod, which will be described below.

FIG. 5 shows a diagrammatic sketch of one embodiment of wireless telemetry pod 40 that is adapted to be threaded or joined onto the lower end of any commercially available well plug, thereby converting it to a WiSP. This provides a different embodiment of a WiSP than that shown in FIG. 4. Shown in this configuration, a set of onboard batteries 42 drives electronics that senses pressures and temperatures below it. In this case two discrete pressure/temperature data signals are received—from sensor 32 and probe 25. These data are transmitted wirelessly on two channels to a receiver above by two receiver/transmitters, 44 and 46. Additional channels of data may be added.

FIG. 6 shows a commonly used suspension plug. In one embodiment, the bottom part of the plug is removed and replaced with wireless telemetry pod 40. While various well-known bridge plugs and lock type flow control devices are well proven and commercially available, the communication plug disclosed herein offers proven technology coupled with functionality that provides the “total” barrier philosophy that is needed for deep water operations. In addition, the present system has a more robust barrier system over and above operator requirements and current industry standards. This greatly reduces the risk profile associated with implementation of new technology or techniques in a deep water operating portfolio.

The following sequence of drawings shows the general steps required to utilize the communication plug in conjunction with the DDBS and wireless communication to provide a well control system with pressure barriers that can be verified from the surface of the sea. FIG. 7 shows offshore drilling rig 110 over cemented and cased well 10 with Blow Out Preventer (BOP) 112 mounted on wellhead 68 and marine riser 66 used in drilling the well still in place. In this example, open hole section 69 has been drilled below the shoe of casing 64. Installation of sand control completion equipment is necessary in many wells, particularly offshore wells, and will be illustrated here. Alternatively, a casing liner may be placed and cemented in open hole section 69 or section 69 is not present. At this stage of well construction well safety may be maintained by two barriers: the BOP and kill weight fluid.

FIG. 8 shows running in the well of DDBS 70 on its running tool 70 a and work string 70 b in a single trip into the well. Barrier valves 73 and 75 are run in the open position and ported sleeve 76 is preferably closed. Stinger prong 70 c may be used to manipulate barrier valves 73 and 75 and ported sleeve 76. The first operation is to set lower packer 74, then test it. This is accomplished by manipulating running tool stinger prong 70C, closing barrier valve 75 and pressuring up. At this point, telemetry sub 16 is alive and active, measuring and transmitting PT data, which may be collected by a memory pod on running tool 70A or transmitted to surface in real time by telemetry provided in work string 70 b. Such telemetry may be by electric line, electromagnetic, acoustic or other system. The second operation is to set upper packer 72, then test it. As running tool prong 70 c is withdrawn from the well, ported sub 76 is opened by an appropriate method and second barrier valve 73 is closed. The data collected by the memory pod on the running tool may be analyzed when it is withdrawn or analyzed in real time.

FIG. 9 shows running in the well of DDBS 70 on separable work string 201, having on/off attachment 205 at a selected location in the work string. Upper work string 201 a may be removed, as shown in FIG. 3, so that WiSP 30 may be installed in a well. Lower work string 201 b may have repeaters 210 and 212 attached.

FIG. 10 shows communication plug 30 installed in casing 62 below BOP 112 with riser 66 still attached. Pressure/temperature probe 25 hangs by cable 14 from communication plug 30. Probe 25 is located as closely to telemetry sub 16 as possible, preferably within 10 feet. At this point in operations, five barriers are in place—two in DDBS 70, one in communication plug WiSP 30, the kill weight fluid barrier in the wellbore and BOP 112.

FIG. 11 shows well 10 after removal of the riser and BOP. DDBS 70 and communication device 30 now provide four barriers—barrier valves 73 and 75, plug 30 and kill weight fluid in the wellbore. Work Ship 115 has been moved on location near well 10. ROV 116 may be deployed from ship 115.

FIG. 12 shows a total Subsea Isolation System (SIS) in place in a vertical well and the communication from the downhole electronics. Telemetry sub 16 measures temperature and pressure data between the barrier valves and transmits that information electromagnetically to probe 25, hanging near it. Data are preferably transmitted in short bursts at regular and useful intervals so as to conserve battery power. Probe 25 receives the EM signal and transmits that to communication plug 30 on Channel 1. Sensor 32 measures pressure/temperature below communication plug 30 and transmits that to plug 30 on Channel 2. Plug 30 takes the data from Channel 1 and Channel 2 (preferably EM signals) and transmits it (preferably EM) to transducer 19, from which acoustic signals are sent to work ship 115. A suitable acoustic system for use in transducer 19, for example, is provided commercially by Nautronix.

The electronics will be able to transmit data for up to six months, deriving power from onboard batteries in each of the tools. Less frequent data bursts extend battery life; more frequent shorten battery life. This frequency of data bursts can be programmed into the downhole electronics before being run in the well.

FIG. 13 shows a horizontal well equipped with a subsea isolation system similar to that shown in FIG. 12 for a vertical well, except the well also has a separable work string. Lower work string 201(b) is shown. The upper work string has been removed to allow installation of plug 30(b). Three verified pressure barriers are now supplied by DDBS 70 and plug 30(b) and possibly a third barrier may be provided by kill weight fluid in the wellbore, making four pressure barriers in the well—more than industry and regulatory requirements.

FIG. 14 shows a vertical well after removal of plug 30(b) and work string 201. The well is now ready for installation of upper completion equipment at the seafloor using work ship 115 and ROV 116. FIG. 15 shows a horizontal well at the same stage of development.

When deployed in horizontal or highly deviated wells, operational sequences are similar to those described for vertical wells; however, the communication processes are normally different, since a combination of electromagnetic and acoustic relay devices will be required in a horizontal well, as shown in FIG. 2. Since acoustic signals in casing are attenuated by cement and wellbore noise can corrupt data relayed in this manner, the separation distance between relays can be selected taking into account results of cement bond logs in the interval of the well where acoustic signals are to be transmitted and other well-specific data.

Although the discussion of operations herein has been limited to the initial completion of a well, it should be understood that the apparatus and methods disclosed herein can to be applied to all intervention or abandonment operations in well, offshore or land. Intervention operations include all types of workovers of wells.

Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims. 

I claim:
 1. A dual downhole barrier assembly having a flow conduit therethrough for placement in a well, comprising: a first and a second barrier valve in the flow conduit; a first and a second packer to seal outside the flow conduit, the first packer being deeper than the second packer; and a pressure transducer and a wireless telemetry apparatus between the first and second packer for transmitting pressure data.
 2. The assembly of claim 1 further comprising a ported sleeve disposed between the first and second barrier valve.
 3. The assembly of claim 1 wherein the second packer is a retrievable packer and further comprising a polished bore receptacle below the second packer to allow removal of a portion of the conduit above the first packer.
 4. The assembly of claim 1 further comprising a polished bore receptacle above the second packer.
 5. The assembly of claim 1 wherein the first and second barrier valves are operable by a stinger prong.
 6. The assembly of claim 2 wherein the ported sleeve is operable by a stinger prong.
 7. A well suspension plug, comprising: a body having a sealing surface thereon adapted for setting in a well casing; a probe below the body containing an acoustic receiver; and a wireless telemetry pod in the body for communicating data collected below the body or on the body.
 8. The plug of claim 7 further comprising a sensor on or below the body and below the sealing surface.
 9. A method for verifying pressure barriers in a well, comprising: deploying the dual barrier assembly of claim 1 on a work string in a single trip into the well; manipulating the first and second barrier valves by movement of a stinger prong; and sending pressure data to a receiver where the data are communicated to test the first or the second packer of the dual barrier assembly.
 10. The method of claim 9 wherein the receiver is disposed on a work string or running tool and the pressure data are communicated to surface.
 11. The method of claim 9 wherein the work string further comprises a storage device and the pressure data are stored and later retrieved.
 12. The method of claim 9 wherein the work string includes an on/off attachment and further comprising removing a top portion of the work string by operation of the on/off attachment and placing the suspension plug of claim 7 in the well and communicating the data to surface through the plug.
 13. A method for placing verifiable pressure barriers in a well, comprising: deploying the dual barrier assembly of claim 1 on a work string and running tool in a single trip into a well; and removing at least a portion of the work string so as to deploy the suspension plug of claim 7 in the well.
 14. The method of claim 13 further comprising providing transmitters and receivers to transmit pressure data from the plug to a ship. 